Camped overnight at MacGregor Mountain campsite, climbed up the Black Canyon trail to the Bighorn site where deep snow began. Struck off-trail climbing moderately through forrest to an abrupt treeline. Hiked up the SE ridge (steep but easy) dodging small snow fields until to blocky summit
No one had signed the register since 2009 so I claim first (dry) ascent in 2010

For people worrying about where to leave the trail; it really doesn't matter. If you are travelling up, you are going the right way.

Also, I'd say that Mummy is the first major mountain in RMNP to summit without snowshoes, as the SE ridge is rather windswept meaning there are few patches of snow en route to the summit